A working machine such as a hydraulic excavator is provided with a hydraulic pump for feeding pressure oil to hydraulic actuators (hydraulic cylinders, hydraulic motor). This hydraulic pump is driven by an engine as a drive source. This engine is electronically controlled. An engine controller that performs the electronic control has a storage means, in which plural different upper limits of a target rpm for the engine as set beforehand and work modes set corresponding to the respective upper limits have been stored, and a control means for controlling the engine rpm by selecting one of the upper limits of the target rpm as stored in the storage means. In an operator's cab of the working machine, a switch is arranged as a work mode instruction means that is operated by an operator to instruct a work mode. According to the instruction from the switch, the engine controller selects the upper limit of the target rpm corresponding to the work mode. According to an engine output required for work which is about to be performed by the working machine, the upper limit of the target rpm for the engine is, therefore, selected from the plural upper limits, thereby making it possible to reduce a waste of an engine output and to economically use the working machine.
It is, however, cumbersome for the operator to change the work mode whenever the work details are changed. The operator, therefore, tends to leave the engine controller as instructed in the work mode in which an upper limit of the rpm higher than a required engine rpm is selected, whereby a problem has arisen in that the change of the upper limit of the target rpm is not made appropriately.
Accordingly, a means has already been contrived to limit the operator's selection of a work mode by a manager such as the owner of the working machine. This means has a control panel and a change management unit. The control panel is arranged together with the above-mentioned switch as the work mode instruction means in the operator's cab, and enables the input of a code number, while the change management unit sets the controller in one of two states, one being a state that allows to change the work mode upon input of the code number through the control panel, and the other a state that limits the changing of the work mode (see Patent Document 1).
Conventional remote management systems for working machines also include those which manage a control program and data of a control unit arranged on a hydraulic excavator by a server of a base station via communication lines. The remote management systems of this kind include those which, when the attachment of the front working mechanism of the hydraulic excavator has been changed, specifically when a bucket of a standard size has been changed to a wide bucket or a breaker or an arm of a standard size has been changed to a long arm, rewrite a control program and data, which are stored in the control unit and correspond to control of the front working mechanism having the bucket of the standard size, to contents corresponding to control of the front working mechanism having the broad bucket or breaker or rewrite a control program and data, which corresponds to control of the front working mechanism having the arm of the standard size, to contents corresponding to control of the front working mechanism having the long arm.
In such a remote management system, control units of hydraulic excavators each have a communication unit (hereinafter called “the machine-side communication unit”), and a base station has a server and a storage unit. Stored in the storage unit are the serial numbers of the hydraulic excavators, the models of the respective serial numbers, standard control programs and data for the respective models, control programs and data corresponding to various attachments of the respective models, and the like. To a communication unit (hereinafter called “the base station-side communication unit”) arranged in the server, the control unit of each hydraulic excavator transmits information on an attachment change by the machine-side communication unit. By using the information stored in the storage unit, the server which has received the above-mentioned information identifies the serial number of the hydraulic excavator as an originator of the information on the attachment change, selects the control program and data corresponding to the new attachment of the identified hydraulic excavator, transmits these control program and data to the machine-side communication unit of the hydraulic excavator as the originator by the base station-side communication unit, and makes the control unit of the hydraulic excavator rewrite the previous control program and data (see Patent Document 2).